1. Field of the Invention
This invention relates to weighing scales having electrical outputs, and especially to "bathroom" scales having digital output indicators.
There is a continuing need for inexpensive means for accurately measuring forces and weights both for commercial and for personal purposes. For instance, many people are concerned about their weight for both health and appearance reasons, and consequently there is a great need for weighing scales for personal use, commonly referred to as "bathroom" scales. As a result, there is a constant effort to produce new scale designs which are low in cost, high in accuracy, easy to read, easy to use, durable and shock resistant, and small in size and light in weight.
2. Description of the Prior Art
One of the most serious problems in providing high accuracy in a household "bathroom" scale arises from the need for providing an accurate zero reading. Most mechanical scales are provided with mechanical zero calibration adjustment dials which must be constantly readjusted in order to assure the accuracy of the scale from the standpoint of establishing an accurate zero reading. Scales with electrical output indicators, which are usually digital readout scales, suffer from this same problem. One prior solution to this problem in an electrical readout scale has been to provide a kick-switch which is to be operated by the user, such as by pressing a button in the side of the scale housing, before stepping on the scale. The actuation of that switch serves to provide a zero calibration for the scale to provide a subsequent accurate weight measurement in terms of eliminating a zero error.
However, there are various disadvantages to such an arrangement. For instance, an extra motion is required by the user, which is undesirable. Furthermore, a user who is unfamiliar with the scale will not know how to use it correctly. Still further, the mechanical disturbance of the scale mechanism caused by kicking the kick-switch is not conducive to scale accuracy and to long scale life.
The present invention is believed to overcome these problems.